CD49b (cluster of differentiation 49b) is a protein which in humans is encoded by the CD49bgene.

The CD49b protein is an integrin alpha subunit. It makes up half of the α2β1 integrin duplex. Integrins are heterodimeric integral membrane glycoproteins composed of a distinct alpha chain and a common beta chain. They are found on a wide variety of cell types including, T cells (the NKT cells), NK cells, fibroblasts and platelets. Integrins are involved in cell adhesion and also participate in cell-surface mediated signalling.[1]